1. Field of the Invention
The present invention relates to a single cascade multistage turbine that functions as a multistage turbine while having a single cascade of rotor vanes.
2. Description of the Related Art
Conventionally, a multistage turbine is known as a device for efficiently converting the energy contained in a fluid into power. A multistage turbine is a turbine that repeats a process consisting of converting energy contained in a fluid into power by a rotating cascade of rotor vanes, then guiding the fluid with reduced pressure to another cascade of rotor vanes located downstream, and converting the energy in the fluid into power.
However, with the multistage turbines currently used, in the case where the peripheral velocity of the blades is set to a particular value, in order to convert the energy contained in the fluid into power with a sufficient degree of efficiency even when the working fluid is at high pressure, it is necessary to increase the number of turbine stages, in other words the number of cascades. Increasing the number of cascades in a multistage turbine immediately creates the problems of complicating the turbine construction, increasing manufacturing cost and reducing ease of maintenance.
Therefore, the remaining problem of enabling the energy contained in the fluid to be efficiently converted into power in the same way as a multistage turbine, without increasing the number of cascades needs to be resolved.